Objective: To identify linear determinants of human aquaporin 4 (hAQP4) in the context of HLA-DRB1&z.ast;03:01. Design: In this controlled study with humanized experimental animals, HLA-DRB1&z.ast;03:01 transgenic mice were immunized with whole-protein hAQP4 emulsified in complete Freund adjuvant. To test T-cell responses, lymph node cells and splenocytes were cultured in vitro with synthetic peptides 20 amino acids long that overlap by 10 amino acids across the entirety of hAQP4. The frequency of interferon γ, interleukin (IL) 17, granulocyte-macrophage colony-stimulating factor, and IL-5-secreting CD4 + T cells was determined by the enzyme-linked immunosorbent sport assay. Quantitative immunofluorescence microscopy was performed to determine whether hAQP4 281-300 inhibits the binding of anti-hAQP4 recombinant antibody to surface full-length hAQP4. Setting: Academic neuroimmunology laboratories. Subjects: Humanized HLA-DRB1*03:01 +/+ H-2b -/- transgenic mice on a B10 background. Results: Peptide hAQP4 281-300 generated a significantly (P<.01) greater T H1 and T H17 immune response than any of the other linear peptides screened. This 20mer peptide contains 2 dominant immunogenic 15mer peptides. hAQP4 284-298 induced predominantly an IL-17 and granulocyte- macrophage colony-stimulating factor T H cell phenotype, whereas hAQP4285-299 resulted in a higher frequency of T H1 cells. hAQP4 281-300 did not interfere with recombinant AQP4 autoantibody binding. Conclusions: hAQP4 281-330 is the dominant linear immunogenic determinant of hAQP4 in the context of HLADRB1&z.ast; 03:01. Within hAQP4 281- 330 are 2 dominant immunogenic determinants that induce differential T H phenotypes. hAQP4 determinants identified in this study can serve as diagnostic biomarkers in patients with neuromyelitis optica and may facilitate the monitoring of treatment responses to pharmacotherapies.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Clinical Neurology